Weight gain is linked to our body’s natural rhythms as well as the amount of calories we consume, according to new American research.

The study, carried out by scientists at Ohio State University, found that eating while exposed to light changed the human metabolism — and caused weight gain.

Someone eating at night with a light on would gain more weight than someone eating the same amount of calories in the dark, said Laura Fonlen of Ohio State.

Her group studied mice to come to the conclusion. “Although there were no differences in activity levels or daily consumption of food, the mice that lived with light at night were getting fatter than the others,” she said.